Mostly Harmless
by SeizeTheDayBrokenAngel
Summary: How Tony and Bruce become best friends, or 'Why being a genius and a fanboy is not always a good combination.' Tony and Bruce have a lot in common, and one of those things happens to come in the form of a book with 'Don't Panic' written in large, friendly letters on the cover. Avergers fic with a dash of H2G2


Pairings: Bruce/Tony (friendship), implied Steve/Tony, implied Natasha/Clint

Rated: PG-13 for mild language and innuendo

Author's notes: I do not own the Avengers or any Marvel characters, nor do I own the Infinite Improbability Drive, The Hitchhiker's Guide to the Galaxy or any of Douglas Adams' characters. They own everything; I'm just playing in the sandbox.

* * *

Bruce was awakened by the shrill ring of his alarm clock after far too few hours of sleep. Exhaustion threatening to pull his body under but he fought against it. People needed his help. So he would help them. _Although one of these days, maybe I should try to find a job that lets me sleep in every once in a while, _he thought groggily. He reached over to the table beside his bed and fumbled with the off button without looking over. The ringing continued. Confused, he grabbed his glasses and slipped them on before looking at the clock. 4:15 a.m. Belatedly, he realized it was not, in fact, the alarm clock that was ringing, but rather the satellite phone from S.H.I.E.L.D. that Nick Fury had given to him in case he was 'needed' again. _Well that's not a good sign._ Sighing he got out of bed and started searching for the phone without turning the light on. He knew it couldn't have gone far. The ringing stopped.

So did Bruce. _Maybe they don't need me after all, _he thought. _It's not like Fury to give up if it was important._

But sure enough, the ringing started up again. Bruce finally located the phone and flipped it open, muttering 'Banner,' by way of greeting into the mouthpiece.

"Brucey-baby, what took you so long?," came a voice that was _definitely _not Director Fury's.

"Tony?" Bruce said, looking down at the phone in his hand to make sure it was the satellite phone he picked up and not his cell phone. "How did you get this-, no wait. I know. You hacked into S.H.I.E.L.D's systems again, didn't you?"

"Again?" said Tony, innocently. "What makes you think I ever _left_ the system? Fury told me not to hack the system again, so I didn't," he continued sarcastically.

"What do you want Tony," muttered Bruce as he flopped back down onto his bed. Conversations with Tony were never short lived, and if he got lucky, maybe the drone of Tony's voice would put him to sleep.

"Hmmm… Tall, blonde and muscular. Patriotic. Adorably naïve. Unbelievably flexible," said Tony glibly. "And he should be able to do that thing with his-"

"TONY," said Bruce, cutting Tony off before his description became embarrassingly graphic. Last time, he hadn't cut Tony off in time and hadn't been able to look Steve in the eye for weeks. "I mean, what do you want with _me _at 4 o'clock in the goddamn morning?"

"What, so a guy can't call his BFF and chat about their love life?" Tony replied. "Why Bruce, I'm hurt! I thought we had something special."

"Tony, I was sleeping. And I'm actually working out here," he said, adding, "Not tinkering around in a lab like _some people_" as there came a rather loud crash over the line, and Tony swore profusely and threatened to chop the offending robot up and make high-tech pregnancy tests out of it.

"Well, I have tried to call during regular office hours," said Tony petulantly. "But _somebody_ keeps ignoring my phone calls."

Bruce groaned and slung his free arm across his eyes and let out a sigh. It was true, every time he had heard Tony's personalized ring tone (AC/DC's Back in Black; even though he kept changing it to a normal ringer, somehow it always switched back to Iron Man's unofficial theme song, as Tony called it. Bruce suspected Tony had a hand in this.) he dutifully ignored it. Most days he just wasn't in the mood for dealing with the eccentric and irritating billionaire playboy genius, even if he was a philanthropist some days and his best friend to boot. Other days, Bruce was just plain tuckered out from running the free clinic here in one of India's poorest neighbourhoods.

"Tony, if this isn't important, I'm going back to bed," he said, ignoring Stark's comment. "Good night."

Bruce made to flip the phone shut but his hand froze in place at the sound of Tony's voice.

"Well I was just calling to let you know that Operation _Heart of Gold_ is a go, but if you'd rather play Doctor Quinn Medicine Woman, then that's ok. I'll just show it to Pepper. Or Rhodey. Or, scratch that. Someone who understands and appreciates my genius, actually. Like-"

"Wait, what? You've figure it out?"

At the mention of _Heart of Gold_, Bruce had bolted straight up out of bed, eyes flying open wide. _Impossible. I didn't think he would seriously try to figure it out._ But Bruce's mind had begun to unravel at the implication of the news Tony had given him. He was slowly descending into full-blown fanboy mode.

"If my calculations are correct, and they usually are, then I think I have a decent schematic of the prototype ready to build," he stated. It would have been arrogant, but this was Tony Stark and everything he did was arrogant so you kind of got used to it. "Wanna help, partner?"

Bruce couldn't keep the excitement out of his voice as his mind made calculations. "If I pack now and leave first thing in the morning, I can take a train to Calcutta and be on a plane in the next day or so," he said. His face fell. He was accustomed to how Tony worked. "You'll probably be close to finished by the time I got there."

"Naw, I got this charity event in a few hours so I won't be in the lab," Tony said cheerily. "And you'll be here when I get back so we can start then."

"But-"

"No buts. I've already sent the jet. See you when you get here," he said. And with that Tony hung up.

Bruce stared at the phone in his hand, incredulously. Then with a squeal of joy that would put the teenage fangirls to shame, he jumped up and began packing.

When Bruce had first met Tony, all those years ago when Loki first threatened the Earth and before the Avengers had officially formed, he had mostly remained silent in awe at the man whose genius was an inspiration and a driving force behind his own work. He gaped silently as the man he looked up to (professionally, not personally; you'd have to be brain damaged to use Tony as a role model in life) told him he _admired his work, _then threw in a jab about 'the other guy' and continued on his merry way. Working with Tony had been interesting at first to say the least. Tony's brain never seemed to shut off, or slow down and was able to work on several different problems at once. Sometimes this made holding a conversation very difficult because Tony switched gears faster than the speed of light and it was dizzying trying to keep up. Between focusing on the task at hand, trying to keep up to Tony's running conversation (some days it resembled more closely an external monologue) and dodging the sharp things Tony liked to poke him with, there wasn't much room for Bruce to think about saying anything. And at the end of the day, he'd be exhausted and unable to keep up with Tony's relentless energy (_Where does he get it from? I never see him sleep)_ and he would fall asleep in one of Tony's guest bedrooms in Stark Towers while Tony went off gallivanting across the city.

Eventually, Bruce started being able to keep up with Tony and managed to get in little snippets of conversation in between Tony's ranting at his robot helpers and a running monologue of what seemed to be every thought that slipped into his mind. That was how the two became friends, instead of just 'co-worker,' or as Tony referred to him: 'someone who can finally keep up with me intellectually.' They actually had a lot in common, which surprised Bruce and often times during their projects they would debate the merits of the original Star Wars trilogy versus the new series (although they both agreed that Jar-Jar was an abomination), they argued over which incarnation of the Doctor was better (Tony had a thing for David Tennant and Bruce preferred the older episodes but agreed that the current series wasn't half bad) and commented on the eerie physical similarities of Steve and the Human Torch, Johnny Storm (they looked nearly identical, which made Tony's eyes glaze over with an emotion Bruce _really _didn't want to know about).

But it was an offhand comment that Bruce made one day that cemented their friendship forever. Tony was going on about giving the rest of the Avengers a tagline that summed them up succinctly (his being 'genius billionaire playboy philanthropist') and he had asked Bruce what he thought his was.

Bruce stopped and thought about it for a moment before replying, "Mostly harmless" with a small smirk that belied his casually offhand manner. There was a clatter of tools on the work bench and Bruce looked up quickly, only to find Tony staring at him open mouthed. Bruce raised an eyebrow but said nothing.

"Did you just-, are you serious-, wait," He swallowed hard and gave his head a brief shake. "What's the answer to life, the universe and everything?" he asked.

"Forty-two," Bruce replied with a grin. The dumbstruck look on Stark's face didn't disappear.

"Dr. Banner," he deadpanned. "I would open mouth kiss you on the lips right now if I thought you swung that way and didn't think Steve would get adorably, disproportionately upset."

Bruce laughed and from that day on, they were virtually inseparable.

As it was, several hours later when Bruce debarked from the jet and was driven over to Stark Towers by Tony's friend and valet Happy, he found the lab quiet and still – a sure sign that Tony was still out on the town. He made himself a cup of tea, had JARVIS turn on some classical music and began looking through the schematics on Tony's work bench.

It wasn't hard to find the documents he was looking for and he began to look over the dozens of pages of calculations and research Tony had done in his absence. Not to see if there were any errors – because honestly, how would he know? – but in an attempt to see how Tony had created the impossible thing in the first place.

The Infinite Improbability Drive, as noted in The Hitchhiker's Guide to the Galaxy, is a wonderful new method of crossing vast interstellar distances in a mere nothingth of a second, without all that mucking about in hyperspace. A physics student discovered it by a lucky chance after years of respectable physicists failing to create a machine which would generate the infinite improbability field needed to flip a spaceship across the mind-paralyzing distances between the furthest stars and consequently admitting grumpily that it was virtually impossible. He proved them wrong.

Bruce and Tony had one night attempted to translate the materials and physics needed for such a machine into something they could try on Earth, following the consumption of several alcoholic concoctions that Tony had dubbed "Gargle Blasters" which somehow managed to taste like coconuts, metal and battery acid. Despite the taste, Bruce had been assured that they were perfectly safe by Tony, who quipped 'I've almost died once because of alcohol, I assure you I don't mean to do it again." Bruce doesn't remember how far they got with the project or if it even made sense, but he does remember the hangover he had the next morning which was bad enough to keep him in darkened rooms for days. Tony didn't fare much better.

But apparently, their drunken escapade hadn't been forgotten by Tony and it seems the genius had spent a fair amount of time over the past few years coming up with a half-way decent looking plan to attempt it.

As Bruce was looking over the plans, he heard Tony stumble into the lab and looked up. Tony had showered and his still-wet hair was sticking up in all directions. He was wearing his 'Zaphod says yes to Zaphod' t-shirt that Bruce had gotten him for Christmas one year and still seemed a little drunk, judging by the bleary way he was trying to focus on Bruce. A grin broke out on Tony's face.

"Whaddaya think?" he asked.

"I see you actually intend on using 'a nice hot cup of tea' for the Brownian Motion producer," Bruce said with a chuckle. "But what do you intend to use for the Bambleweeny 57 Sub-Meson Brain? I don't know if JARVIS has the computing power for that… No offense JARVIS."

"_None taken Dr. Banner. Sir, shall I reveal the prototype?"_

"Yes please JARVIS," Tony said with a grin.

"But I thought-"

"Ah, ah ah. Hold your horses there Green Machine," Tony chided. "And just look."

At the far end of the lab, a panel was rising to reveal the newest model of Iron Man's suits. This one was almost entirely white with only minimal gold trimming, instead of the usual red and gold look Tony was fond of. Tony walked over to the new suit and pressed a button behind what would be the ear of the helmet. The face-hatch opened but the suit was empty.

"Bruce," Tony said, motioning Bruce forward. "I'd like you to meet DOUGLAS."

"Tony, I don't get it. Did you name the suit DOUGL-aaaaaah!" said Bruce, as the suit booted to life and a British voice greeted Tony, with a "Hello Zaphod."

_Oh. _Bruce thought.

Oh.

"Bruce, this is DOUGLAS, my newest AI, little brother to faithful JARVIS here and the computer requirements for our Infinite Improbability Drive," Tony said with a chuckle.

Bruce turned to Tony with a grin and said, "Well, what are we waiting for?"

Even with the newest suit already built and all the plans carefully mapped out, it still took the two of them four days with only six hours of sleep between them (Four for Bruce when he started getting so frustrated from lack of sleep on day three that Tony ordered him out of the lab to take a nap before the 'other guy' made an appearance and destroyed their work; two for Tony when Bruce thought he was just staring really hard at a particular problem they had run in to, when in fact Tony had fallen asleep with his eyes open. Even now, Bruce still thought it was creepy.) to finish the whole thing. It was nearly midnight on a Friday when they deemed everything complete and had contingency plans in place for anything that could conceivably go wrong (this wasn't what they were concerned about however – when dealing with infinite improbability, it was what would _inconceivably _go wrong that would be a problem). Tony was ready to try the suit immediately, but Bruce talked him letting them both catch a few hours of sleep before testing out the Infinite Improbability Drive. However, Tony also managed to talk Bruce into going out for celebratory drinks before they slept. Luckily for both of them, the bartender didn't know how to make a 'Gargle Blaster.'

Saturday morning, well more like afternoon, after a quick breakfast Bruce and Tony headed down to the lab, giddy as school girls, to test out the armour dubbed 'the Heart of Gold.' Pepper had vacated the building, saying she wanted nothing to do with Tony's next attempt at getting himself killed, and that someone had to run Stark Interprises since Tony obviously wasn't interested. Steve had joined them for breakfast but seemed hesitant to intrude on Bruce and Tony's 'play dates' as he put it, so with a quick kiss on Tony's cheek he left to spar with Clint in the training room.

As Tony donned the armour, Bruce took a seat at the work bench with both his and Tony's cell phones nearby, just in case. Today, Tony was wearing his 'Beeblebrox. Just be glad he's out there.' T-shirt and had a grin plastered across his face. Bruce could barely contain his excitement too. The armour booted up and DOUGLAS asked for security clearance 42.

"Life, the universe and everything, man," Tony said, with a wink towards Bruce.

"_Thank you Zaphod, would you like me to include Ford in today's protocol run-through?"_

Bruce raised an eyebrow at Tony. "Really? We're roleplaying now?"

"It's actually a security measure, Oh Jade One. How easy do you think it is to obtain a sound clip of me saying my name?" Tony replied.

"Well, pretty easy, but couldn't JARVIS recognize the difference between your voice and a sound clip?" Bruce countered.

"JARVIS, yes. DOUGLAS, no. Unfortunately Mr. Improbability here is lacking the security software that JARVIS has so I had to come up with a phrase that would be nearly impossible for people to recreate or steal, hence the new name. Just be happy I didn't decide to call you Arthur."

The suit gave a beep to remind Tony that it was still waiting for an answer.

"Sorry DOUGLAS, no not today. It'll be just me on this one," Tony told the AI.

"_Right you are sir. All systems are on-line and ready to go."_

Tony grinned wolfishly at Bruce before closing the face plate. "Ready for this, my friend?"

"As ready as we'll ever be Stark. Hit it."

"DOUGLAS, could you please initiate the Infinite Improbability Drive? And make it a good one."

"_Of course sir. So long, and thanks for all the fish."_

The suit began to glow, faintly at first, then the golden light became brighter and brighter until Bruce had to look away.

_Calculating current improbability at two to the power of two hundred and seventy-six thousand seven hundred and nine to one against. Please remain calm. _

The resulting explosion caught them both off guard. Luckily, Tony was at the centre of the explosion and remained relatively unscathed except for a few minor burns (one in a rather _unfortunate_ location). Bruce on the other hand escaped harm by inadvertently turning into the virtually indestructible 'other guy.' Everything else in the lab wasn't so lucky.

Tony had learned from his past mistakes and when constructing Stark Towers, had turned his lab into a bomb shelter – protecting those inside from whatever befell the outside, and those outside from any explosions that could – and more often that Tony would admit, _did_ – happen inside the lab. The only warning that the rest of the Avengers team had that anything was wrong was JARVIS's alarm sounding throughout the tower.

The team ran to the lab and Steve, reaching the doors first with a worried look on his face, manually overrode the door lock system and pried the doors open as the blast had warped them in their frame. Smoke billowed out and somewhere in the room he heard a coughing voice order JARVIS to vent the smoke outside. Almost immediately, the room began to clear and Steve could make out two shapes surrounded by debris. He stepped inside and Clint and Natasha slowly followed. When the smoke cleared enough to see, the trio gaped at the sight. Before them, for unknown reasons, the Hulk was now a fantastic shade of cherry red and twice his size – which was considerable to begin with. But the sight that was most shocking was Tony, standing amid the broken pieces of his latest suit, sporting what were clearly _breasts. _Amply breasts, if Tony wanted to be objective about it. Not to mention curves.

Clint and Natasha paused for a moment, then doubled over laughing, clutching at each other to keep from falling over. Even cherry Hulk started chuckling.

Steve just stood there and stared.

Tony ran a hand through his short (but significantly longer than before) hair and scratched his chin. Which was suspiciously lacking the magnificent five-day growth of beard that he had before. He groaned. Luckily the improbability drive hadn't altered his intelligence, and he managed to deduct that the transformation was _entirely too thorough_ for his liking.

"Figures," he said to no one in particular.

Steve continued to stare at Tony, in a manner that suggested his brain had or was dangerously close to circuiting. Tony sighed.

"JARVIS, see if you can get DOUGLAS's black-box data and figure out how long this particular improbability will last," he said. "As for you two, not a word to anyone about this, do you hear me?"

It was highly likely that Clint hadn't, in fact, heard anything but his own breathless giggles but Natasha was slowly regaining her infamous blank faced composure, when suddenly Clint managed to choke out "But, Thor-" before collapsing into fresh gales of laughter on top of Natasha, who lost her tenuous grip on sanity as well. Tony sighed again.

"As for you," he said turning to the still open-mouthed Steve. "Bedroom. Now. If I'm going to be humiliated, I might as well enjoy-"

But the ringing of each team member's cell phone cut him off. JARVIS answered Tony's cell phone remotely and patched the caller through what remained of the speakers in the lab.

"Stark? We've got a problem and you aren't going to believe this," came an incredulous sounding Agent Coulson.

Tony looked around the room again and then back down at himself. "Try me," he muttered under his breath.

"Fine, we're on our way," he said loud enough for Coulson to hear him. JARVIS disconnected the call.

Heaving another sigh, Tony turned to the Hulk. "Looks like you're going to have to sit this one out until you can fit through the door buddy, they're only made to accommodate regular sized you."

Hulk smashed his fists into the ground in displeasure but stayed where he was. Steve helped Natasha pick Clint up off the floor where he was trying to get his laughter back under control.

Tony pulled off the broken armour and suddenly stopped dead still.

"Aw, man, none of my armour is going to fit properly now!" he said, gesturing to his chest.

Clint saw the motion and collapsed boneless on the floor again, tears springing to his eyes.

"Fine we're leaving you here then," Steve managed to say finally, as he, Tony and Natasha made their way from the lab to the jet that waited to take them off to their next improbable problem.

Later that night, when the team was back recuperating at the Tower and the improbability meter had gone back to normal – changing Tony back and turning the Hulk green again – Clint and Natasha sat perched on the window ledge in Natasha's bedroom. They sat in companionable silence for a while before Natasha silently slipped her cell phone from (_Wait,_ thought Clint, _where _did_ she pull that phone from, she's still in her cat-suit) _somewhere, and opened the photo gallery to reveal a picture she had taken of Tony – or _Tonya_ as they had taken to calling Tony now – in all his feminine glory. Clint choked on the question he was about to ask Natasha (he was really getting curious as to where she kept the phone) and yelped as her iron grip fastened itself around his arm to prevent him from falling off the window sill. Unable to control his laughter, he let Tasha pull them both backwards into the room and managed to roll out of the fall without hurting anything. Together they collapsed helplessly in to a heap of laughter on the floor, until Clint realized that Tasha was sitting practically in his lap wearing not much more than a second layer of skin. The both sobered and exchanged a loaded look, before quickly moving on to a different – and yet thoroughly enjoyable – form of entertainment.


End file.
